Arcuate coil winding and assembly for axial gap Electro-Dynamo Machines (EDM)

ABSTRACT

An axial gap EDM deploys as a stator coils a series of two parallel serpentine windings that each circumscribe an arc segment of a circle. Each arc segment that forms the stator winding assembly is powered as a separate phase. The two winding are readily formed by shaping one or more wire segment. Preferably the parallel winding are arranged to overlap with a half period rotational offset such that the radial directed serpentine segments of that are disposed above and below the stator disk are interlaced when viewed in projection through the disk. In one embodiment, each series of serpentine winding are separated by a gap so that they can be inserted on the stator disk from the edge. A separate rotor disk is adjacent each side of this stator disk. In another embodiment, each series of serpentine winding are separated by a gap, so they can be inserted to surround a single rotor disk which has two series of magnets disposed on opposite sides.

CROSS REFERENCE TO RELATED APPLICATIONS

None

BACKGROUND OF INVENTION

The present invention relates to axial gap electro-dynamo machines.

Axial gap dynamo electric machines deploy stators and rotators that aregenerally in the shape of parallel and adjacent planar discs, with oneof more rotators attached to an axle that passes though the center ofeach disk.

The stator comprises multiple windings that generally wrap across theradial direction of the disc. A Lorenz force is generated by theinteraction with magnets arranged along the periphery of the rotor disc.A more detailed description of this technology can be found in the U.S.Pat. No.'s 4,567,391; 4,578,610; 5,982,069; and 5,744,896, all of whichare incorporated herein by reference.

The inventors have recognized that axial gap EDM's are ideally suitablefor Vertical Axis Wind Turbine (VAWT) designs. VAWT offers a number ofadvantages over conventional Horizontal Axis Wind Turbine (HAWT), suchas lower maintenance costs and increased durability and reliability.VAWT installations are believed to present a significantly lower hazardto migrating birds as HAVT systems, as well as

While VAWT systems are also more economically viable in remote locationsthan 100+kW HAWT systems, there is an ongoing need to improve theefficiency of such machines as well as lower their capital cost soreduce the cost of electrical power derived from this renewable energyresource, and make small to medium size facilities more economicallyviable for say small communities or even the individual homeowner.

Accordingly, it is a general object of the invention to improve thequality and economic viability of large scale axial gap electro-dynamomachines (EDM) for use as generators and motors.

It is a more specific object of the invention to provide a moreefficient method winding the stator coils of such generators and motors.

It is an additional objective of the invention to provide a moreefficient method of stator assembly for large scale axial gaps EDM's.

It is a further objective of the invention to provide improved methodsof thermal management of heat generated with the stator structure.

It is a further objective of the invention to provide the above benefitsat least in part through an improved efficiency through theconcentration of the magnetic field with respect to it's interactionwith the stator structure.

SUMMARY OF INVENTION

In the present invention, the first object is achieved by providing anaxial gap dynamo machine wherein the stator coil has an upper at leastarc shaped serpentine wire segment, a lower at least arc shapedserpentine wire segment. Each serpentine path is made up of a series ofconnected wire segments in the order of a radial segment, an innertangential segment, a second radial segment, an outer tangentialsegment. The upper and lower segments are joined at the periphery andspaced apart to provide a gap for a rotor plate having at least onesequence of magnets disposed in a common plane.

A second aspect of the invention is characterized in that a plurality ofarc shaped segment are inserted around the sides of the rotor disk toform a complete winding covering the rotor disk, with each segmentconnected as separate phase for power or rotary motion generation.

Yet another aspect of the invention is the method of forming the arcshaped serpentine coil assemblies by first forming an insulated wireinto a continuous coil and then wrapping the coil around at least onepreform to form bends that define at least a portion of the serpentinepath in at least one common plane.

A still further aspect of the invention is the method of forming thestator structure or assembling a stator structure to surround the rotordisk by first encapsulating the arc shaped serpentine coil segments in adielectric thermally conductive medium, such as fiber reinforcedconcrete. The arc shaped segments having a sideways U-shaped crosssection are then inserted around the rotor disk.

The above and other objects, effects, features, and advantages of thepresent invention will become more apparent from the followingdescription of the embodiments thereof taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a stator winding according to a firstembodiment of the invention.

FIG. 2A is a cross-sectional elevation of the stator coil of FIG. 1showing the related rotor and attached axle structure.

FIG. 2B is a partial plan view of a portion of the stator winding.

FIG. 2C is an enlarged partial section through a wire that comprises thewinding of FIG. 1.

FIGS. 3A and 3B are alternative embodiments for the arrangements ofmagnets on the rotor disk with an EDM having the stator coil shown inFIG. 1

FIG. 4 is a perspective view of a stator winding according to anotherembodiment of the invention.

FIGS. 5A and 5B are alternative embodiments for the arrangements ofmagnets on the rotor disk with an EDM having the stator coil shown inFIG. 4.

FIG. 6 is an exploded view illustrating a preferred arrangement forlocating the terminals of a stator winding of the type shown in FIG. 1or FIG. 4

FIG. 7A is a cross-sectional elevation of a plurality of stator coilsand related rotor structures according to another embodiment of theinvention.

FIGS. 7 B, C and D illustrate the three-phase wiring of the stator coilsin FIG. 7A.

FIG. 8 is a schematic elevation comparing the available orientation ofthe magnets on the rotors for the embodiments of the three phase wiringwith the stator windings shown in FIG. 4.

FIG. 9 is a schematic elevation comparing the available orientation ofthe magnets on the rotors for the embodiments of the three phase wiringwith the stator windings shown in FIG. 1.

FIGS. 10A, B, C, D and E illustrates an embodiment of a preferred methodof winding the stator coils.

DETAILED DESCRIPTION

Referring to FIGS. 1 through 10, wherein like reference numerals referto like components in the various views, there is illustrated therein anew and improved axial gap EDM with an arcuate coil winding, generallydenominated 100 herein.

In accordance with the present invention, FIG. 1 illustrates inperspective view a stator coil 100 with arcuate coil winding. The statorcoil 100 subtends an arc of a circle to be assembled with additionalstator coils as a disk shaped stator structure 250 as will be describedin the FIG.'s that follow with respect to alternative embodiments.

Stator coil 100 comprises an upper arc shaped serpentine wire segment120 and a lower arc shaped serpentine wire segment 110, which areconnected by at least one wire segment 25 that traverses the separatebut parallel planes within which each of segments 110 and 120 aredisposed. In each of the wire segments 110 and 120, each serpentine pathis made up of repeating series 105 of connected wire sub-segments in theorder of a radial segment 5, an inner tangential segment 10, a secondradial segment 15 and an outer tangential segment 20. The electricalconnections in this embodiment are made at terminals marked as phase (φ)and neutral (N) as the outer periphery of the arcuate coil segment 100.A portion or segment of stator coil upper segment 120 is shown in Planview is illustrated in FIG. 2B, with separate reference arrow in eachFigure indicating the radial (r) and tangential (t) coordinate axes. TheX-axis corresponds to the principle axis of axle 10.

As the upper 120 and lower 110 segments are joined at the periphery bywire segment 25, they are also spaced apart to provide a gap having thethickness represented by reference numeral 101 for inserting aroundeither a rigid stator plate or a rotor plate having magnets.

FIG. 2A illustrates an alternative embodiment of the invention of anaxial gap EDM 200 with a plurality of stator coil 100 (shown only on theleft side of the figure) surrounding a single rotor disk 205. This rotordisk 205 in this embodiment has magnets 215 arrayed the upper side andmagnets 215′ arrayed on the opposite or lower sides. It should beunderstood that it is the intention in the preferred embodiments thateach stator disk 250 when assembled into the working EDM comprise aplurality of stator coils 110 assembled to surround at least one rotordisk 205, as shown in cross-sectional elevation in FIG. 2B. It is morepreferable to first form a plurality of wedge of half circle stator disc2100 by potting the dual layer stator coil 100, and then slipped orinserted it edgewise with respect the dual layer rotor disk 205. Therotor disk 205 is in a rotary co-axle connection to the axle 10 andhaving at the periphery of the upper 211 and lower 212 surface an array210 of permanent magnets, portion of which are illustrated in atransverse of tangential cross-section in FIGS. 3 and 5.

FIG. 2B is a section view through a winding 130 in cross-sectioncontaining a plurality of insulated wire bundles 140. It should beappreciated that wire 140 can be round, but is alternatively of a flatcross-section to form a ribbon like shape. Preferably each segment ofthe wire contains multiple insulated strands, each plural wound in theserpentine shape. FIG. 2C is a plan view of segment 105. FIG. 2Crepresents a preferred embodiment wherein a thermally conductivedielectric potting or encapsulating media 150 surrounds at least theportion 5 and 15 of the stator coil shown in FIG. 2B. Such a preferredform of an encapsulating media is fiber reinforced cement. In essence,it is more preferred that the cement that encapsulates the statorwindings, when solidified form the stator disk itself. Alternatively,another disk provided onto which the stator coil is then attached, andthen covered by cement.

Alternative embodiments for arranging and orienting the permanentmagnets of array 210 are shown in FIGS. 3A and 3B. Each of these figuresis an elevation facing the edge of the rotor structure with only theradial segments of the stator winding shown. The direction of currentflow in each winding segment is represented by an “o” for currentflowing backwards from the plane of the Figure (the X-t plane) an “x”representing current flowing forward from the plane of the Figure, thatis toward the viewer.

It first should be noted that the rotor requires that magnets aredisposed in 2 overlapping layers. In FIG. 3A the magnets in the upperlayer are stacked over the magnets in the lower layer. The magnets inthe upper layer are denoted as 125 and the magnets in the lower layerare denoted 125′. In contrast in FIG. 3B, the magnets in the upper layerare offset or staggered to lie in between in pair of adjacent magnets inthe upper layer.

In a first pair of overlapping pair of 225, magnets the upper magnet isoriented with the North Pole, “N”, facing up. However, the lower magnet125′ is inverted so that the North Pole now faces down. This orientationis necessary, as for example in the case of a motor, so that the currentgoing into the plane in the upper coil segment 1215 exerts a force onthe rotor disk, in interacting with magnet 215, which is in the samedirection as the opposite flowing current out of the plane in the lowercoil segment 1125. It should be noted that the current in the lower coilsegment 1125 interacts with magnet 215′.

However, in the configuration shown in FIG. 3B, the upper and lowermagnets can be oriented with there north poles facing the samedirection, as the staggering of the upper magnets 215 with respect tothe lower magnets 215′ avoid the simultaneous application of opposingforces on the rotor.

In accordance with another embodiment of the present invention, FIG. 4illustrates in perspective view a stator coil with two arcuate coilwinding 100. Each arcuate or wedge shaped stator winding 100 and 100′subtends a half circle and are mounted to straddle the disk shaped rotorstructure 205 as will be described in the FIG.'s that follow.

Each of the stator coil 100 and 100′ in FIG. 4 comprises an upper arcshaped serpentine wire segment 120 and a lower arc shaped serpentinewire segment 110, which are connected by at least one wire segment 25that traverses the plane separating the upper and lower half is curvedto follow diagonal path across the curved X-t surface such that theupper and lower arc segments are offset laterally by a half repeat unit105. This offset is more apparent in FIG. 5A, which is a cross sectionalelevation of the X-r plane the relationship between the stator structureand the rotor magnets 215.

Thus, FIGS. 5A and 5B are elevations facing the edge of the rotorstructure with only the radial segments of the stator winding shown.Again, the direction of current flow in each winding segment isrepresented by an “o” for current flowing backwards from the plane ofthe Figure (the X-t plane) an “x” representing current flowing forwardfrom the plane of the Figure, that is toward the viewer. It should benoted that because of the transverse segment 25 the upper coil 120 andthe lower coil 110, the radial segments of each winding are laterallystaggered in the tangential direction. This staggering provides for atleast two alternative orientations of magnets 215.

In FIG. 5A a plurality of magnets 215 are arrayed adjacent to each otherin a single layer. Each magnetic 215 is oriented with opposite polarityof the adjacent magnet 215. In FIG. 5B the magnets are disposed in 2overlapping layers with the magnets in the upper layer 215 are stackedover the magnets in the lower layer 215′. Because of the lateralstaggering of the coil segments of opposing sides of the stator, themagnets 215 in the upper layer need not be oriented in the oppositeorientation of the magnetic 215′ immediately below in the lower layer.This is in contrast to the configuration shown in FIG. 3A and providesthe benefit of a more concentrated magnetic field to increase power ofthe motor or the efficiency of the EDM when operated as a generator.

FIG. 6 is an exploded perspective view of the rotor structure in FIG. 4showing in more detail that a connecting wire segment 25 traversesbetween upper arc shaped serpentine wire segment 120 and a lower arcshaped serpentine wire segment 110 disposed in parallel planes spacedapart by gap 101. The electrical connections in this embodiment are madeat terminals marked as phase (φ) and neutral (N) as the outer peripheryof the arcuate coil segment 100.

FIG. 7A is a cross-sectional elevation of a plurality of stator coilsand related rotor structures in an EDM according to another embodimentof the invention. Stacked stators labeled B, C and D surround a rotorhaving a plurality of rotor disks 205 connected by common axial 10. Eachof the FIGS. 7 B, C and D illustrate the three-phase wiring of thestator coils in FIG. 7A, with the plurality of three type B stators inFIG. 7B all being wired to the first phase of the power circuit.Likewise, In FIG. 7C, the plurality of three type C stators in are allwired to the second phase of the power circuit. Further, as shown inFIG. 7C, the plurality of three type D stators in are all wired to thethird phase of the power circuit. This configuration simplifies thewiring connections at the terminals of each stator segment, and avoidsthe possibility of short circuit if the insulating layer of the wiringin any segment is damaged. In such case, it may be preferable to wireeach of the three upper stator segments together in series, but for aterminal that connects across the upper and lower stator segments, withthe lower three stator segments also being connected in series. In thiscase each of the assembled stator sets that surround a rotor in thecompleted EDM has a signal adjacent phase and neutral terminalconnection.

FIG. 8 is a schematic elevation showing one embodiment of theorientation of the magnets on the rotors 205 for the embodiments of thethree phase wiring with the stator structure 250 shown in FIG. 4. Eachof the rotors 205, 205′ and 205″ surrounded by a stator has an upper andlower set of magnets in the, each magnet is oriented with N pole facingup. On the terminal rotors 205 a and 205 b that only have a singlemagnet layer, each magnet is oriented with N pole facing up

FIG. 9 is a schematic elevation of another embodiment showing analternative orientation of the magnets on the rotors for the embodimentsof the three phases of wiring with the stator windings shown in FIG. 1.Each of the rotors 205, 205′ and 205″ is surrounded by the stator 225and has an upper 215 and lower 215′ set of magnets. Each upper set ofmagnet 215 is oriented with N pole facing up, while each lower set ofmagnets 215′ is oriented with the North Pole facing down.

FIGS. 10A, B, C, D and E illustrate an embodiment of a preferred methodof winding the stator coils into arc shaped segment using a preform as aguide or track for the wire and the bends or folds therein. First, asshown in FIG. 10A insulated wire 1001 is wound around a circular form toform a coil of predetermined diameter with a multiple coil segment sothat it terminates preferably in adjacent end terminals 1010 and 1020,forming loop 1030.

FIGS. 10B and 10C are plan and elevation views respectively of oneembodiment of preform type winding frame 1150 used to shape loop 1030into the configurations shown in FIG. 1 and FIG. 4. Winding frame 1150is substantially circular plate 1151 having an inner series of pegs 1161extending from at least one, and preferably both sides. At the peripheryof circular plate 1151 is a second series of outer pegs 1162, which asshown in FIG. 10C, also extend to both sides of plate 1151. It should beappreciated that the pegs are spatially arranged in a predeterminedmanner to be disposed at the bending or deflection points of the statorwinding in configuration shown in FIGS. 1 and 4. Thus, the inner pegs1161 are arranged closer to each other than the outer pegs 1162 todefine the wedge shape of each winding segment.

As shown in FIGS. 10D and E, in the next step, the insulated wire loop1030 is next wound into a serpentine coil using a preform, such as theframe and pegs shown in FIGS. 10B and 10C. Thus, it is intended that thepegs be used to bend and then route the wire coil 1030 into a serpentinecoil shape by repeated wrapping around at least an arc of plate 1151,first between outer peg 1162 and the nearest inner peg 1161, then to thenext adjacent inner peg, followed by tight wrapping to the next outerpeg and so on in the same direction under the desired wedge angle issubtended. At this point, winding frame 1150 can be flipped so thatwinding proceed to the other side. Wrapping to the reverse side of frame1150 is shown in FIG. 10E. Alternatively, a segment can be folded overto form sideways facing U shape after wrapping on one side of frame1150.

It should be appreciated that the above method is not limited to theform of the preform shown, but may use bend, wrap or compress theserpentine coil.

While the invention has been described in connection with a preferredembodiment, it is not intended to limit the scope of the invention tothe particular form set forth, but on the contrary, it is intended tocover such alternatives, modifications, and equivalents as may be withinthe spirit and scope of the invention as defined by the appended claims.

1. A stator coil for an axial gap dynamo electric machine thatcomprises, a) wire formed into a first series of serpentine coilsdisposed within a first common plane that defines an upper coil segment,b) wire formed into a second series of serpentine coils disposed insecond common plane that defines a lower coil segment wherein the firstand second common planes are parallel, c) each of said first and secondseries of serpentine coils circumscribing an arced segment of a circleby a series of joined contiguous wire segments that start at the outerperiphery of the arced segment with, i) a first radial segment having anouter end and inner end; ii) an inner tangential segment connected at afirst end to the inner end of the first radial segment; iii) a secondradial segment, having an outer end and inner end, the inner end connectto the other second end of the inner tangential segment, iv) and anouter tangential segment having a first end connected to the outer endof the second radial segment, and an second end disposed on the outerperiphery of the arced segment, d) wherein said first and second seriesof serpentine coils are connected at least at one end by a coil segmenton the outer periphery of the arced segment that is disposed in a planeperpendicular to the first and second common planes and links an outerend of a radial segment of said first series of serpentine coils to anouter end a radial segment of said second series of serpentine coils. 2.A stator coil for an axial gap dynamo electric machine according toclaim 1 wherein the upper coil segment is offset from the lower coilsegment wherein the majority of the radial segments of the each of theupper coil are disposed between the tangential segments of the lowercoil.
 3. A stator coil for an axial gap dynamo electric machineaccording to claim 1 wherein the arc shaped serpentine coil segments areencapsulated in a dielectric thermally conductive medium with each arcshaped segment having a U-shaped cross section.
 4. A stator coil for anaxial gap dynamo electric machine according to claim 3 wherein thedielectric thermally conductive medium is fiber reinforced concrete. 5.An axial gap dynamo electric machine, the machine comprising: a) anaxle, b) at least one rotor disk in rotary co-axle connection to saidaxle and having at the periphery at least one circular array ofpermanent magnets with each magnetic of said disk having an alternatingorientation of the poles with respect to the adjacent magnets, c) astator coil comprising two or more arc shaped segments having a U-shapedcross-section so as to straddle both sides of said rotor disk forgenerating a Lorenz force.
 6. An axial gap dynamo electric machineaccording to claim 5 wherein the rotor disk comprises an upper and lowercircular array of magnets with each magnetic on the upper surface ofsaid disk having an alternating orientation of the poles with respect tothe adjacent magnets on the upper surface, but the same orientation asthe magnet elements in a corresponding array on the lower surface ofsaid disk.
 7. An axial gap dynamo electric machine according to claim 5wherein the rotor disk comprises an upper and lower circular array ofmagnets, wherein: a) each magnetic on the upper surface of said rotordisk has an alternating orientation of the poles with respect to theadjacent magnets on the upper surface, b) each magnetic on the lowersurface has the same orientation as overlaying magnet on the uppersurface of said rotor disk.
 8. An axial gap dynamo electric machineaccording to claim 5 wherein the rotor disk comprises an upper and lowercircular array of magnets, wherein: a) each magnetic on the uppersurface of said rotor disk has an alternating orientation of the poleswith respect to the adjacent magnets on the upper surface, b) eachmagnetic on the lower surface has the opposite orientation as overlayingmagnet on the upper surface of said rotor disk
 9. An axial gap dynamoelectric machine according to claim 5 wherein the rotor disk comprisesan upper and lower circular array of magnets, wherein: a) each magneticon the upper surface of said rotor disk has an alternating orientationof the poles with respect to the adjacent magnets on the upper surface,b) each magnetic on the lower surface is offset in the radialorientation to lie between to magnets on the upper surface of said rotordisk.
 10. An axial gap dynamo electric machine according to claim 5comprising a plurality of rotor disks wherein the plurality of arcshaped segments that comprises the stator coil straddling each rotordisk are connected to the same phase circuit.
 11. An axial gap dynamoelectric machine according to claim 5 wherein the arc shaped serpentinecoil segments are encapsulated in a dielectric thermally conductivemedium with each arc shaped segment having a U-shaped cross section. 12.An axial gap dynamo electric machine according to claim 11 wherein thedielectric thermally conductive medium is fiber reinforced concrete. 13.A process for forming a stator coil for an axial gap EDM, processcomprising the steps of: a) providing a wire, b) forming a first portionof the wire into a serpentine coil having a first segment, c) formingthe adjacent portion of the wire into the second segment of theserpentine coil, d) doubly folding adjacent portion of the wiretraversing the first and second segment such that the each of the firstand second segment are disposed in two parallel planes that are offsetby a gap corresponding to the separation of the double folds.
 14. Aprocess for forming a stator coil for an axial gap EDM, according toclaim 13 wherein the radial segments of the first serpentine coil aredisposed substantially midway between radial segments of the secondserpentine coil.
 15. A process for forming a stator coil for an axialgap EDM, process comprising the steps of: a) providing a wire, b)forming the wire into a continuous coil, c) wrapping at least a firstportion of the wire coil formed in the previous step around a preformthat outlines at least a portion of a first serpentine path of thestator coil that lies in a first common plane.
 16. A process for forminga stator coil for an axial gap EDM according to claim 15 and furthercomprising the step of: a) wrapping at least a second portion of thewire coil not wrapped in the previous step around a preform thatoutlines a second serpentine path of the stator coil that lies in asecond common plane.
 17. A process for forming a stator coil for anaxial gap EDM according to claim 15 and further comprising the step of:a) twice bending adjacent portions of the wire coil between the firstand second serpentine paths so as to dispose the second serpentine coilin a plane parallel but spaced away from the plane of the firstserpentine coil.
 18. A process for forming a stator coil for an axialgap EDM according to claim 15 wherein the first and second serpentinecoil segment are an arc of a circle.
 19. A process for forming a statorcoil for an axial gap EDM according to claim 16 wherein the radialsegments of the first serpentine coil are disposed substantially midwaybetween radial segments of the second serpentine coil.